In the field of start/stop systems, new functionalities within the engine controller are being developed in order to meet the changed demands on the starter actuation, fuel injection, operating strategy etc. For the present method according to the invention, consideration is given to the regulation of the cylinder air charge and the fuel injection of an internal combustion engine in start/stop operation. According to the prior art, in start/stop operation, after the initiation of an engine stop, the throttle flap is closed (for diesel engines for example in order to minimize shut-down juddering) and the enablement of the fuel injection or ignition is withdrawn. The restart of the internal combustion engine is prepared for during the run-down by the opening of the throttle flap and the enablement of the injection or ignition. This is realized within the engine controller by means of rotational speed thresholds, wherein the rotational speed which is used (angle-based updating in accordance with synchronization calculation) is filtered in relation to a tooth-based rotational speed of the engine sensor.
In a conventional start/stop system without the “engagement during run-down” function, there is adequate time available for the preparation of the restart capability of the internal combustion engine by means of said two processes. A restart is initiated only after the detection of a standstill state of the internal combustion engine. At this time, the preparation of the restart is complete, and the time duration of the restart (for example the duration from the setting of the start demand to the attainment of the idle rotational speed) is not influenced.
This changes in the so-called “change of mind” situation with engagement during the run-down. If a restart is demanded by the vehicle driver shortly after a stop demand, it is possible by means of the “engagement during run-down” function for the starter motor to be engaged already during the run-down of the internal combustion engine. The time duration for the opening of the throttle flap and the enabling of the injection and/or ignition are time-critical in this case. The restart capability of the internal combustion engine must in this case be produced punctually at the time of engagement. As a result of the expansion of the start/stop functionality to include “engagement during run-down”, an adaptation of already-existing engine control functions must also be carried out.
Below, a method will be presented which describes the actuation of the throttle flap and the injection for preparation of the restart of an internal combustion engine after “engagement during run-down” in the “change of mind” situation.